1. Field of the Invention
The invention relates in general to handrail apparatus, and more specifically to handrail apparatus which includes a continuous, flexible handrail member which is driven about a guide loop.
2. Description of the Prior Art
U.S. Pat. No. 3,712,447, which is assigned to the same assignee as the present application, discloses a handrail guide system for passenger conveyors, such as escalators and movable walks, which permits the handrail to be both pushed and pulled about a substantially continuous guide loop. This arrangement has many advantages over those arrangements which obtain the tractive force necessary to propel the handrail member by only pulling it around a discontinuous guide loop. The latter arrangement develops a relatively large tension in the handrail member, causing it to wear and stretch. In the hereinbefore mentioned U.S. Patent, the length of the guide loop is initially adjusted to the exact length of the handrail loop.
Despite the fact that large tensions are not produced in the handrail member by the arrangement disclosed in the hereinbefore mentioned patent, the loop length of the handrail changes after initial installation, due to such things as manufacturing variations, inherent changes in the lengths of the materials used in the handrail as the handrail flexes and wears, humidity, temperature, etc. Thus, the guide loop length must be periodically readjusted. Periodic readjustment accommodates permanent changes in the loop length of the handrail, but it does not correct temporary changes such as those due to humidity and temperature.